Heavy tractor-type trucks are designed to tow trailers, and semi-trailers, having large loads for transport of goods, supplies or other freight. Generally, trailers have no engine of their own and are pulled behind a tractor truck. Heavy trucks are generally configured around a chassis frame which forms the superstructure of the vehicle which typically includes an engine, drive train, drive wheels and steering wheels, among other primary components. Further, an occupant cab is supported generally above a front portion of the chassis frame. These tractors also usually have a horse shoe shaped device, also known as a fifth wheel, located toward the rear of the chassis frame and which is designed to receive a protrusion, or kingpin, from the trailer for “hitching” different trailers, one at a time, to the towing tractor.
In current designs, tractor trucks and trailers rely on air pressure rather than hydraulic fluid for brake control. This increases the ease of coupling and uncoupling the trailer from the truck, while also reducing some of the problems associated with hydraulic systems.
In order to supply the trailer with air for control of the brakes and/or other systems, air hoses from the truck must be connected with the trailer. Generally trucks have two types of air lines that must be interconnected with the trailer for controlling trailer brakes and which are often referred to as service and emergency air lines. Air pressure in the service air lines, also known as control or signal lines, is controlled by the foot brake or a trailer hand brake. In general, the air pressure in the control or signal lines varies depending on how much the foot brake is depressed by the operator/driver. The emergency air lines, also known as supply lines, supply air to the trailer's air tank(s) and control the trailer's emergency brakes. Emergency brakes are designed to be applied if the pressure in the emergency lines fall below a particular value.
Pneumatic interconnection between the tractor and the trailer is facilitated using well known “glad-hand” devices. For connection, a glad hand from the truck can be coupled or mated with a glad hand from the trailer thereby providing an air-tight seal and a secure physical connection. Also, there can be a glad hand for the different types of air hoses, including one or more for the service lines as well as the emergency line.
Trailers can be designed to connect with the air lines of the tractor at any of a number of locations, but the two typical possibilities are at the backside of the truck cab or near the rear end of the chassis frame. In order to facilitate attachment in either of these typical locations, today's tractor trucks employ sets of glad-hand connections at each of the two positions. Due to these different sets of glad hand connections, one or the other will be connected to a particular trailer, but never both. Furthermore, the set that is connected to the trailer must be provided pressured supply air, while it is preferable that none is supplied to the other non-connected set of glad hands.
In the past, in order to switch between the available connections in dependence upon to which the trailer was connected, manual reconfiguration of the air delivery system by the operator was required. For example, multiple valves might have to be turned or plugged, hose connections disconnected and reconnected elsewhere, as well as other actions that may need to be taken depending on the number and design of the involved interconnections. Such requirements increase the amount of labor and time costs for an operator. They also increase the possibility that the connections will not always be properly achieved with obvious negative results.
Therefore, what the present solution appreciates and addresses is the need for a simple, but effective system for shifting between the several possible connections with minimal manual involvement on the operator's part.